This invention relates to hand held tools for driving nails, and more particularly to a cost effective device which is simple and reliable due to a few number of parts to protect the hand and accurately guide the nail being driven by an elongated indexed piston.
Numerous nail driving and guiding devices have been used and are long known in the art. The importance of these and improved devices has increased over the past few years due to the rapid growth of the number of home owners and others doing their own construction work. These do-it-your-self owners and amateur carpenters have much difficulty in holding and guiding a nail to be driven. The probability of striking themselves somewhere on their body is very high. The increased medical costs resulting from accidents has made the purchase of protection devices much more cost effective in recent years. In addition, the easier the tool is to use, and the more it instructs the user in its use, the better. The hand held tool of this invention provides such a device.
Typical nail guiding and driving tools invented over the years are disclosed in U.S. Pat. Nos. 535,503, 924,054 and 4,676,424. In U.S. Pat. No. 535,503 a pair of spring controlled arms hold a nail as it is being driven by a plunger. The plunger is inserted into a tube that guides the plunger and holds the arms that support the nail. The end of the nail is not indexed to the end of the arms prior to driving the nail.
The disclosure of U.S. Pat. No. 924,054 shows a nail driving plunger with a variable diameter slidably mounted in a tubular body with a channeled guiding member at one end. A thumb piece is located in the tubular body to control the location of the plunger within the tubular body. The striking surface is at the end of the plunger being an relatively small area for striking. A number of individual pieces are used to make the tubular body. A similar tool is disclosed in U.S. Pat. No. 4,676,424 that also includes a pin to limit the movement of a punch in a metal sleeve. The movement of the punch is further controlled to not drive the nail more than necessary into an object being nailed. The punch includes a head adapted to receive direct blows. The tool of this invention works best with a single nail size.
A number of prior art tools have guide sleeves in the form of handles shaped for gripping with one hand. Two such references are U.S. Pat. Nos. 2,839,754 and 3,391,842. In U.S. Pat. No. 2,839,754 a flexible housing encompasses a steel guide member having an axial bore with a striker rod mounted within the bore. A tubular friction member attached to the striker rod is placed between the flexible housing and the steel guide member. A hand guard of limited width beyond the housing is a part of the flexible housing. The shank of a fastener or nail is gripped with a guide arrangement and the position of the fastener during driving is indicated by indices on the periphery of the tubular friction member. No indexing for different size fasteners is indicated. The tubular friction member frictionally absorbs the rebounds of the driving punch by gripping the housing.
The patent of U.S. Pat. No. 3,391,842 discloses a guide sleeve in the form of a handle which is provided with a projection to provide some limited protection for the hand of the operator. In another embodiment a separate handle portion is made to offset the handle portion containing a driver. The driver is supported and stopped in its driving motion by a tubular extension placed within the handle.
Discrete plunger or piston retainer devices are disclosed in U.S. Pat. Nos. 952,571; 992,547; 1,089,112; 1,158,430; 2,199,833; 2,672,610; 2,896,209; and 4,437,602. A body or barrel portion provides the outer housing for the plunger in U.S. Pat. No. 922,547, 1,089,112 and 1,158,430. As disclosed in each of these patents, the movement of the plunger within the barrel portion is limited by a ratchet device where an engaging device attached to the barrel engages the ratchet grooves on the plunger. The ratchet grooves are closely spaced and the spacing is not associated with the size of different fasteners being driven.
Friction devices to keep the plunger or driver engaged in the barrel or housing are disclosed in U.S. Pat. No. 952,571; 2,199,833; 2,896,209; and 4,437,602. Each of these patents disclose some type of friction device attached to the housing that holds a shank portion of the driver within the housing at various positions when the fastener is being driven. The shank is held by the friction alone without grooves or other holding components. The U.S. Pat. Nos. 952,571, 2,199,833 and 2,896,209 also disclose an additional means to hold the fastener as it is being driven.
In U.S. Pat. No. 2,672,610 discloses a combined nail driver and set for finish nails which has a spring wire which cooperates with an indicator groove to indicate the distance that the finish nail has been set below the surface of the wood. There is no indication as to the starting position for driving the finish nail.
The present tools provide only limited assistance in driving a nail and numerous components are used to make the tool. Most of these tool components are easily damaged by a misguided blow of the hammer and they require adjustments and maintenance. Striking surfaces are often very small causing more misguided blows to occur. Little protection is also provided for the hand of the operator. No indicating means to properly position different sizes of nails is provided prior to the start of the driving operation. A need exists to have a minimum number of impact resistant components which can be economically manufactured and can be operated to protect the user. A tool that helps the user adjust for different sizes of nails is also needed.
Accordingly, an object of the present invention is to provide a simple, reliable and cost effective hand held tool for driving nails and at the same time instruct the user as to a proper initial setting for different sizes of nails.
Another object of the present invention is to provide a hand held tool that has a portion to protect the hand of a user from being hit when the nail is being driven. A tool that can be safely held in a correct position by one hand when driving the nail from almost any position is also part of this object.
Yet another object of the present invention is to provide a hand held tool which has a striking surface which is easily struck by a hammer or other driver device. In addition, if the tool is struck by the hammer, the object is to have essentially no damage to the tool.